Growing crops such as grains, beans, hay, and the like are cut at harvest using a cutting header. Typically the knife on a cutting header comprises a knife bar extending along the front lower edge of the header, with triangular knife sections extending forward from the bar. The exposed side edges of the knife sections are sharpened and move laterally back and forth, cooperating with guards attached to the front lower edge of the header to slice the crop stems.
The guards comprise pointed guard fingers extending forward, and the knife moves back and forth along the edge of the header in a slot cut laterally through the guard fingers. In addition to cooperating with the knife to cut the crop, the guards serve to protect the knife sections from breakage when contacting stones and like obstructions.
Crops sometimes are lying close to the ground making them difficult to cut. Some plants are inherently short, while others may fall down when they reach maturity, or be pushed down by heavy rain or hail.
The knife of a conventional cutting header is a few inches above the ground when the header is in its lowest position, such that very short or downed crop material will pass under the knife and be lost. Crop lifters of various kinds have been developed that are attached to the header and provide a ski member that extends forward from the knife and rides along the ground ahead of the knife, following the ground and moving up and down relative to the knife as the orientation of the header with respect to the ground varies with field contours. A lifting arm extends rearward at a shallow angle from the front of the ski member back and over the knife. The front end of the ski member slides under the crop stems and lifts them up and they then slide rearward along the top of the lifting arm and over the knife to be cut and fall onto the header.
In one type of crop lifter the ski member that rides on the ground is pivotally attached to the header so as to be able to move up and down to follow the ground. In another common type of crop lifter the ski member is fixed to the header instead of pivoting, but is made of spring steel so that same may flex to move up and down to follow the ground. The crop lifters are attached to the header, often via the guard fingers, by a wide variety of mechanisms, many of which provide a “quick attach” feature that allows the lifter to be removed and replaced quickly.
The pivoting crop lifters are somewhat more complicated and expensive, since they include parts that pivot with respect to each other. The flexing lifters are simple, comprising one of the variety of mechanisms for attaching them to the header, and then a springy ski member extending forward along the ground, and a lifting arm extending rearward and upward from the front end of the ski member.
Flexing spring steel crop lifters are disclosed for example in U.S. Pat. Nos. 3,742,690 and 4,120,138 to Schumacher II et al., and 6,655,120 to Schumacher et al. As can be seen, the ski member is attached to the point of the guard finger and the flexing portion extends forward from the point of the guard finger. Thus the ski member must extend far enough forward to provide a sufficient length from the point of the guard to the front end of the ski member to allow the ski member to flex through the required range of movement. Consequently the prior art flexing crop lifters extend a significant distance forward of the guard fingers. Thus the lifters are subject to damage when passing through dips or ditches in the field, and during turns they move laterally through the crop, such that crop stems can be pushed over and away from the knife, and thus be lost.